Search results for " Complement"

A thermodynamically consistent nonlocal formulation for damaging materials

2002

A thermodynamically consistent nonlocal formulation for damaging materials is presented. The second principle of thermodynamics is enforced in a nonlocal form over the volume where the dissipative mechanism takes place. The nonlocal forces thermodynamically conjugated are obtained consistently from the free energy. The paper indeed extends to elastic damaging materials a formulation originally proposed by Polizzotto et al. for nonlocal plasticity. Constitutive and computational aspects of the model are discussed. The damage consistency conditions turn out to be formulated as an integral complementarity problem and, consequently, after discretization, as a linear complementarity problem. A n…

Emergence and Phylodynamics of Citrus tristeza virus in Sicily, Italy

2013

Citrus tristeza virus (CTV) outbreaks were detected in Sicily island, Italy for the first time in 2002. To gain insight into the evolutionary forces driving the emergence and phylogeography of these CTV populations, we determined and analyzed the nucleotide sequences of the p20 gene from 108 CTV isolates collected from 2002 to 2009. Bayesian phylogenetic analysis revealed that mild and severe CTV isolates belonging to five different clades (lineages) were introduced in Sicily in 2002. Phylogeographic analysis showed that four lineages co-circulated in the main citrus growing area located in Eastern Sicily. However, only one lineage (composed of mild isolates) spread to distant areas of Sici…

A quantitative analysis of Educational Data through the Comparison between Hierarchical and Not-Hierarchical Clustering

2017

Many research papers have studied the problem of taking a set of data and separating it into subgroups through the methods of Cluster Analysis. However, the variables and parameters involved in Cluster Analysis have not always been outlined and criticized, especially in the field of Science Education. Moreover, in the field of Science Education, a comparison between two different Clustering methods is not discussed in the literature. Conceptions of students about modeling in physic are investigated by using an open-ended questionnaire. The questionnaire is analyzed through Clustering methods. The clustering results obtained by using the two methods are compared and show a good coherence bet…

Le Geometrie dei numeri duali

I numeri duali furono introdotti per la prima volta da William Kingdon Clifford (1845-1879) nel 1873, come estensione dei quaternioni (biquaternioni), nell’ambito dello studio dei numeri ipercomplessi. In seguito, furono chiamati così da Eduard Study (1862-1930) [Study 1902], il quale ne fece poi oggetto di studio [Study 1903]. Già nel 1885 Arthur Buchheim (1859-1888) [Buchheim 1885], aveva rintracciato l’origine dei duali in Clifford e si era soffermato sulla (sostanziale) differenza tra l’introduzione dei biquaternioni in Hamilton e in Clifford. Nel 1906, in perfetto accordo alle teorie esposte da Study nel 1903, Joseph Grünwald (1876-1911), introdusse i numeri duali come u+vε, dove u e v…

Efficient numerical methods for pricing American options under stochastic volatility

2007

Five numerical methods for pricing American put options under Heston's stochastic volatility model are described and compared. The option prices are obtained as the solution of a two-dimensional parabolic partial differential inequality. A finite difference discretization on nonuniform grids leading to linear complementarity problems with M-matrices is proposed. The projected SOR, a projected multigrid method, an operator splitting method, a penalty method, and a componentwise splitting method are considered. The last one is a direct method while all other methods are iterative. The resulting systems of linear equations in the operator splitting method and in the penalty method are solved u…

Numerical Study of Two Sparse AMG-methods

2003

A sparse algebraic multigrid method is studied as a cheap and accurate way to compute approximations of Schur complements of matrices arising from the discretization of some symmetric and positive definite partial differential operators. The construction of such a multigrid is discussed and numerical experiments are used to verify the properties of the method.

Active macro-zone approach for incremental elastoplastic-contact analysis

2013

SUMMARY The symmetric boundary element method, based on the Galerkin hypotheses, has found an application in the nonlinear analysis of plasticity and in contact-detachment problems, but both dealt with separately. In this paper, we want to treat these complex phenomena together as a linear complementarity problem. A mixed variable multidomain approach is utilized in which the substructures are distinguished into macroelements, where elastic behavior is assumed, and bem-elements, where it is possible that plastic strains may occur. Elasticity equations are written for all the substructures, and regularity conditions in weighted (weak) form on the boundary sides and in the nodes (strong) betw…

An iterative method for pricing American options under jump-diffusion models

2011

We propose an iterative method for pricing American options under jump-diffusion models. A finite difference discretization is performed on the partial integro-differential equation, and the American option pricing problem is formulated as a linear complementarity problem (LCP). Jump-diffusion models include an integral term, which causes the resulting system to be dense. We propose an iteration to solve the LCPs efficiently and prove its convergence. Numerical examples with Kou@?s and Merton@?s jump-diffusion models show that the resulting iteration converges rapidly.

Chess Thinking and Configural Concepts

2012

The purpose of this work is to connect chess and mathematics education. First, we introduce the idea of configural concepts in chess thinking and then we outline a scheme to show the phases of chess reasoning and how to apply this idea to some conflictual situations. We conclude this work proposing two research problems in introducing chess in mathematical classroom activities.

COULD STUDY AND PLAY OF CHESS IMPROVE SOCIAL INTERACTIONS? RE PORT OF AN ITALIAN CASE STUDY.

2012

Aim of this work is to improve the social interactions within a math classrooms (6 th grade), introducing a chess activity during the curricula hours. The theoretical framework upon which this research is based consists of: Vygotsky’s Theory of child developmen t (Vygotsky, 1986), the knowledge objectification theory (Radford, 2006) and theory of configural concepts (a personal review of Fischbein’s theory of figural concepts). We will discuss the results of an experimentation that has the purpose to create an appropriate environment wher e the students develop the abilities to solve and pose problems.